At TED2010, Bill Gates unveiled his vision for the world's energy future, describing the need for "miracles" to avoid planetary catastrophe and explained why he's backing a dramatically different type of nuclear reactor (Terrapower). The necessary goal? Zero carbon emissions globally by 2050.

In my view in this talk Bill gets a lot right, including the woefully inadequate level of energy R&D investment, the misplaced investment in deploying uneconomically viable technologies, the inadequacy of current alternative energy solutions, the need to be cheaper, and the need to try a lot of different approaches to improve the odds of success. These perspectives have led him to conclude that nuclear power is the best available option, and putting his money and time where his mouth is he has invested in and promoted a high-risk nuclear power venture called Terrapower. With his investment in Terrapower he also perhaps inadvertently has created a big angel investment model for what is necessary to get the ball rolling given the inability of the capital markets or government to address the problem.

Terrapower represents the big R&D investment approach aiming to produce carbon free energy that costs less than energy today. It is using around $100M to produce paper designs. It will need billions and a decade to build a test reactor and billions more and another decade to design and deploy production reactors. It ultimately has to overcome the public skepticism of nuclear power and a whole host of technical problems. It’s definitely the big R&D approach but relative to the scale of the energy business it is tiny. It is small even relative to US investment in clean power which mostly funds deployment of technologies that can never realistically compete but satisfies various political constituencies.

In contrast StratoSolar is solar not nuclear and is a small R&D approach. It builds on existing PV and construction technologies and materials. A relatively small investment of $10M builds a test platform in 18 months rather than computer simulations. Incremental investments develop production platforms and then assemblies of production platforms. It generates competitively priced electricity in production, so it needs no subsidies. It simply needs R&D investment. Energy is so large scale that ramping up production initially may need government guarantees to bolster investor confidence.